RE: [CAD_CAM_EDM_DRO] Re: stepper vs servo

> -----Original Message-----
> From: elson [mailto:elson]On Behalf Of Jon Elson
> Sent: Thursday, August 09, 2001 1:50 PM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: Re: [CAD_CAM_EDM_DRO] Re: stepper vs servo
>
>
> info.host@... wrote:
>
> > > Or, on the otherhand, don't overload the stepper and it will be just
> > > as reliable and accurate.
> > >
> > > Mariss
> >
> > When you see kits for upgrading Sherlines and the likes to CNC are the
> > motors (100 - 150oz/in) given as per their peak torque or their constant
> > torque? How much constant torque would it take to run a normal
> sized knee
> > mill like a Bridgeport series 1?
>
> Steppers do not have peak torque. because steppers need to waste
> power just to hold position, they normally run at the continuous rating
> point, and can't be 'boosted' to a higher current for a moment.
>
> Servos DON'T use much power just sitting, and therefore can be safely
> booted to higher current for a moment.
>
> But, steppers do have 'holding torque' and 'running torque'. The holding
> torque
> may be as much as twice the running torque, even at fairly low speed.
>
> I'm using 1/8 HP (continuous) servo motors on my Bridgeport Series 1,
> with 2.5:1 belt reduction ratio, and 5 TPI ballscrews. I calculate about
> 1000 Lbs linear force on the table with this setup.
>
> That motor works out to about 4.4 in/Lb continuous, and 15 in/Lb peak.
>




> Jon
>
>
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